Fabric testing machine



Aug. 18, 1936. A. P. NONWEILER FABRIC TESTING M'ACHINE Filed Aug. 11,1933 2 Sheets-Sheet 1 IN VEN TOR.

ATTORNEY.

1936. A. P. NONWEILER 2,051,269

FABRIC TESTING MACHINE Filed Aug. 11, 1935 2 Sheets-Sheet 2 ATTORNEY.

Patented Aug. 18, 1936 UNITED STATES PATENT OFFME 2,051,269 7 FABRICTESTING MACHINE Application August 11, 1933, Serial No. 684,640

8 Claims. (01. 265-44) This invention relates to improvements in the artof testing fabrics.

In the construction of airplanes it is common practice to treat thefabric used with a liquid, commonly termed dope. This dope serves toprotect the fabric from the elements and to cause a shrinking ortautening thereof. A plurality of coats is usually applied and thedegree of tautness obtained depends partly upon the number of 10 saidcoats, partly upon the composition of the dope, and partly upon a numberof other factors such as type of fabric, temperature, humidity, timeinterval between coats, and method of application. Heretofore, the finalresult obtained by treatment of fabric has been largely a matter ofguess-work. This is necessarily objectionable as'the efliciency of theairplane and the safety of the passengers may depend upon the manner inwhich the fabric is treated and this treatment 20, should be such thatthe fabric offers a surface which is semi-rigid to a predetermineddegree to form a constant air foil. Heretofore, various-deviceshave beendeveloped for testing the tensile strength of the fabrics by recordingthe resistance to stretching action. None of these devices, however, iscapable of solving the present problem wherein the dimensional changesof fabric under shrinkage and the shrinkage forces are studied.

It is therefore one of the objects of the present invention to providean improved fabric testing device which makes it possible to obtain anaccurate record of the behavior of dope and fabric when the dope hasbeen applied to the latter, thus enabling the manufacturer of dope toplace accurate laboratory control on the manufacture, and enabling thebuyer of material to purchase by specification in terms of resistance topressure developed by shrinkage of the cloth in pounds per square foot.

A further object of the invention is to provide a; device as abovedescribed wherein a record is obtained of the shrinkage forces not onlyas they act in one direction on the fabric but in all directions, saidrecord being obtained without changing the position of the fabric andwithout disturbing the top surface by depression or distortion,thusmaking it possible to apply additional coats of .dope while the test isbeing made sothat a study of the effect of time interval between coatsmay also be made.

A more specific object of the invention is to provide a fabric testingdevice in which a hydraulic medium is utilized in transmitting pressureforces to a suitable gauge or recording device.

A further object of the invention is to provide a fabric testing deviceconstructed to measure lineal dimensional changes in the fabric as wellas theresistance to pressure developed by shrinkage of the cloth inpounds per square foot.

A further object of the invention is to provide 5- an improved devicewhich makes it possible to study the effect of the application of dopeor other liquid upon fabric.

A further object of the invention is to provide an improved fabrictesting device, which, while 10 particularlyadapted for use in theaeronautical field, maybe employed in connection with the study of thebehavior of various types of fabrics under various conditions ortreatments.

With the above and other objects in view the inl5 vention consists ofimprovements in the art of testing fabrics, and all its parts andcombinations as set forth in the claims, and all equivalents thereof.

In the accompanying drawings illustrating one 29 complete embodiment ofthe preferred form of the invention in which the same reference numeralsdesignate the same parts in all of the views:

Fig. 1 is a central longitudinal vertical sectional view through thedevice; V

Fig, 2 is an enlarged detail sectional view taken on line 2 -2 of Fig,1;

Fig. 3 is a plan view in perspective of the device; and

Fig. 4 is an enlarged plan view of a portion of 30 the device showing apiece of fabric in testing po-, sition.

Referring more particularly to the drawings, the numeral 5 designates asuitable base which has mounted preferably near oneend thereof a 35cylinder'or tank 6, said cylinder'having its upper end provided with anair valve 1 and having a valve 8 associated with its lower end andcontrolling the flow of hydraulic mediumfrom the tank to a tube 9communicating with a con- 40 duit H].

A short section of tubing l I extending from the conduit I 0communicates with a jacket I 2 surrounding the lower end of the mercurytube l3 of a thermometer l4. v 45 Another, short sectionof tubing l5extending from the conduit ID communicates with a pres-. sure gauge l6of any standard construction.

Another section of tubing ll extending from the conduit 19 communicateswith a central ver- 50 tical port It of a cross-connector I9. A reliefvalve 20 isassociated with the upper end of the duct l8. Thecross-connector H! has four externally threaded extensions 2| the endsof which are recessed as at 22 to form chambers. Four 55 7 lower ducts23 extend from the central duct l8 'to the chambers 22 and four upperducts 24 connect in a similarmanner. A flexible membrane or disc 25,preferably of rubber, is secured over the ends of the extensions 2|.Four cylinders 26 having annular shoulders 21 formed on their j innerends are held in alignment with the extensions 2| against the membranes25 by means 35 on the base.

of nuts 28.

Within each cylinder 26 is a meansof a pin 32.. r V o 7 Four levermembers 33 preferably triangular shaped, are pivoted on rods 34 mountedin blocks The outer ends of the rods 3| r :are pivoted as at 36 in theslotted ends of bolts 31 extending through the levers'33.

The upper end of eachlever 33 carriesl'a hori.- zontally extendingthreaded adjusting rod 38 which is adapted to be operated by means of anut 39.' The inner ends of the adjusting rods extend through the upperends of the levers and h vi es 40 associated therewith for verticalpivoting movement; 7 c

One of the levers 33 has pivoted near the lower end thereof one end of arod 4 land the other end V of said rod extends slidably through a sleeve42 associated with the lowerportion of the lever 33 directly opposite.A' clamp 44 secured to said sleeve 42 supports a gauge 45 having anoperating, button 46. This gauge is preferably of the Starrett type andis adapted to measure'dis: tance of travel or movement. It is operatedby pressure of the outer end of the rod 4| upon the button 46. Theothertwo lever members 33 are connected by a similar r'od4l 'operating'asimilar gauge as shown in Fig. 3.

The conduit 10 which extends below the base I member 5 may be enclosedin a pan 46, said pan being adapted to hold water or other liquid forcontrolling the temperature of the hydraulic, me

' dium in the conduit 10.

In'use of the device it is preferred to employ a section of fabric 41preferably'one foot square and having the corners notched out as at 48;

Each side edge of the fabric is folded over and hemmed to form a tube 49for receiving a bar 50. The bars 50 are then inserted in theclevices 40and held in position by' means of pins 5|.

' Airplane dope is a substance used 'asa protective coating and also asa means. of shrinking and thereby tautening the fabric to such a pointthat it offers to the wind asemi-rigid surface to form aconstant airfoil; This dope usually consists of a solid, a solvent, a diluent and aplaste- V sizerQ :"The solid may be 'nitro cellulose and-is fabric.

adapted to form ;a film on the fabric and behave like a jell of thereversible type that swells as a result of the solvents and then shrinksas the solvent evaporates. ItJiswell-known that the type, character, andrate of evaporationlof the solvent materially affects and controls thedegree of tautening when the materialis'applied to a The purpose of thepresent instrument slidable piston 29 having a slotted outer end 30within which the inner end of a connecting rod 3l is held by V 7 intothe tank Ethrough the air valve 1, the valve pair. I i

all directions will be accurately .indic'atedsimuh sible to determinethe effect of various types of solvents in the dope 'and the amountthereof,

to determine the effect on the particular type of fabric treated and todetermine the effect of temperature, humidity and time interval between5 coats. It also makes it possible to determine the effect of varyingthe amount or type of other ingredients besides the solvent in the dope.

With the fabric in position as shown in Fig, 4 the adjusting nuts 39 aremanipulated to take up the fabric somewhat and next, with a suitablehydraulic medium partially filling the tank 6 and filling the system,air under pressure is forced 8 being closed. When a desired pressure hasbeen built up within the tank the valve 8 is opened thereby creating apressure within the system which pressure is communicated to therubbermembranes 25 due to th'e'fact that the hydraulic medium flows throughthe ducts I8, 23 and'24 into the chambers 22. The valve 8 is kept openlong enough to build up a desired starting pres-' sure indicated by thepressure gauge I6 and for purposes of example we may assume that twentypounds on the gauge is a suitable starting reading. 25

' When the firstcoat of dope is a'pplied'to the testing piece 41 offabric 'it will at first, as before mentioned, cause a general looseningwhich may Q cause the gauge l6 to drop back to 15 When'a second coat ofdope is applied after the first coat 30 has dried, shrinkage will beginand the fabric,

will therefore tend to exert an inward pull on the upper ends of thelevers 33. This will cause an inward movement of the inner ends of therods 3| and through the pistons '29 and'rubber membranes 35 V 25 willexert a back pressure on the hydraulic medium in the system which willincrease the pressure shown on the gauge and the gauge will then, forpurposes of example, move back to twenty pounds. 'Afterthe second coatis dried a third coat may be' applied which'willcause still furthershrinkage and which may increase the reading on the gauge to thirty. Afourth coating will cause additional shrinkage and may cause the gaugeto-rise to sixty. Inasmuch as the gauge employed has avratio of four toone, the final result will be one-fourth of sixty or fifteen, showingthat the dope has acted'on the fabric to exert a force of flfteenpoundsper square foot. I

While the shrinkage is taking place there will also be a movement of thelower rods 4| which I will cause operation of the gauges 45 and thesegauges, as before mentioned, indicate the distance of travel or amountof movement of the fabric during the shrinking process. Theseauxiliarygauges 45 in addition to showing the amount of movement, serve as acheck upon the pressure gauge, as by use of the device it will be foundthat a certain reading in the gauge I 6 should result ina predeterminedreading in the gauges 45. If these gauges do not suitably check 7 up, itmaybe assumed that there is a leak in the" hydraulic system. V ,7

An important feature of the present invention re'sidesfin theuse of thefour lever members each pair of which acts at rightangles to theotherWith this arrangement the shrinkage in taneously and through a commonmeans, eliminating the necessity of shifting the fabric to obtainreadings in both directions. This therefore makes it possible to applyonecoat of dope after 7 j another without in any way disturbingthefabric on the device and to thereby study all of the effects ofvariation in the composition of the dope, of temperature, humidity,method of application and type of fabric with relation to tautening ofthe fabric.

The device therefore makes it possible for the manufacturer of dope toplace accurate laboratory control on the manufacture thereof to producea specified result in the fabric and also permits the buyer of thefabric which has been treated to purchase on a specification basis. Thusdifferent requirements of different users in connection with the degreeof tautness of the fabric may be easily taken care of in an accuratemanner.

The expression means responsive to movement of the levers as used in theclaims refers to the mechanism associated with the levers for creatingpressure in the hydraulic system to operate the gauge l 6. The termlateral pressure as used in the claims is any pressure against a side ofthe fabric such as the fabric is subjected to during use in aeroplanes.The resistability of the fabric to lateral pressure depends upon thetautness developed as a result of the shrinkage and therefore a study ofthe effect of the shrinkage in producing various degrees of tautnessgives a study of the resistability of the fabric to lateral pressure.

Although only one form of the invention has been shown and described itis obvious that various changes may be made therein and that theinvention may be utilized in other adaptations, and all such changes arecontemplated as may come within the scope of the claims.

What I claim is:

1. A device for studying the shrinkage of fabric under particularconditions comprising four spaced members adapted for readily anddetachably supporting a section of fabric from four sides, said membersbeing movable by the fabric when a change in characteristic of thefabric occurs, and means actuated by said supporting members when somoved for simultaneously indicating the behavior of the fabric in aplurality of directions.

2. A device for studying the shrinkage of fabric comprising four spacedmembers adapted for readily and detachably supporting a section offabric from four sides, said members being movable by shrinkage of thefabric, and means actuated by said supporting members when so moved forindicating the resistance of said fabric to shrinkage force per unitarea.

3. A device for studying the shrinkage of fabric comprising four spacedmembers adapted for readily and detachably supporting a section offabric from four sides, said members being movable by shrinkage of thefabric, and hydraulic means actuated by said supporting members when somoved for indicating the resistance of said fabric to shrinkage forceper unit area.

4. A device for studying the shrinkage of fabric comprising opposedpivotally mounted levers means for supporting a section of fabricbetween said levers, and hydraulically actuated means responsive tomovement of the levers as a result of a change in characteristic of saidfabric for indicating the behavior of said fabric under particularconditions.

5. A device for studying the characteristics of fabric comprisingopposed pivotally mounted levers, means for supporting a section offabric between said levers, a housing having a chamber therein,hydraulic medium within said chamber, a hydraulically operated pressuregauge communicating with said chamber, oppositely positioned cylindersassociated with said housing, pistons movable in said cylinders,resilient means separating said chamber from said cylinders, and meansconnecting said pistons to said levers for transmitting movement of saidlevers caused by a change in characteristic of the fabric to saidpistons to thereby cause a change in the pressure condition of saidhydraulic medium.

6. A device for studying the characteristics of fabric, comprising fourpivotally mounted levers having means in connection therewithconstructed and positioned to support fabric from four sides, a housinghaving a chamber therein, hydraulic medium within said chamber, ahydraulically operated pressure gauge communicating with said chamber,four cylinders projecting from said housing toward said levers, pistonsmovable in said cylinders, resilient means separating said chamber ofthe housing from said cylinders, and means connecting said pistons tosaid four levers for transmitting movement of said levers caused by achange in characteristic of the fabric to said pistons to thereby causea change in the pressure condition of said hydraulic medium.

7. A device for studying the shrinkage of fabric, comprising fourpivotally mounted levers having means in connection therewithconstructed and positioned to support fabric from four sides, a pair ofrods at right angles to one another each having one end connected to oneof said levers and having the free end extending to the opposed lever,and gauges carried by the latter levers and operable by said rods inresponse to a change in characteristic of the fabric.

8. A device for studying the characteristics of fabric, comprisingopposed pivotally mounted levers, means for supporting fabric betweensaid levers, hydraulically actuated means responsive to movement of thelevers as a result of change of characteristic of said fabric forindicating resistability of the fabric to lateral pressure when saidfabric has been subjected to shrinkage, and

mechanically actuated means associated with said levers for indicatinglineal dimensional changes in said fabric as the result of shrinkage.

ARNO PAUL NONWEILER.

